Tube writing pen

ABSTRACT

A tube writing pen, including two writing tubes arranged coaxially one inside the other, the writing tubes communicating with an ink reservoir at their rear ends, and the inner writing tube being arranged for limited the movement in and with respect to the outer writing tube, at least in the axial direction, a cleaning wire projects into the inner writing tube and a drop weight is attached to the cleaning wire at the end thereof adjacent the ink reservoir, the interior of the outer writing tube is widened frustoconically at its writing end, and the outer wall of the inner writing tube has a complementary frustoconcially widened writing zone with a rounded end face.

United States Patent [1 1 Lorenz [451 Aug. 20, 1974 [73] Assignee:Koh-I-Noor Rapidograph, Inc.,

Bloomsburg, NJ.

[22] Filed: Dec. 1, 1972 [21] Appl. No.: 311,178

[30] Foreign Application Priority Data Great Britain 401/260 GreatBritain 401/260 Switzerland 401/260 Primary ExaminerLawrence Charles [57] ABSTRACT A tube writing pen, including two writing tubes arrangedcoaxially one inside the other, the writing tubes communicating with anink reservoir at their rear ends, and the inner writing tube beingarranged for limited movement in and with respect to the outer writingtube, at least in the axial direction, a cleaning wire projects into theinner writing tube and a drop weight is attached to the cleaning wire atthe end thereof adjacent the ink reservoir, the interior of the outerwriting tube is widened frustoconically at its writing end, and theouter wall of the inner writing tube has a complementary frustoconciallywidened writing zone with a rounded end face.

1 Claim, 2 Drawing Figures TUBE WRITING PEN This invention relates to atube writing pen comprising two writing tubes arranged coaxially oneinside the other which, at their rear ends, communicate with a reservoirfor writing-ink or Indian-ink, and a cleaning wire which projects intothe inner writing tube and which, at its rear end, is attached to afalling weight.

In one previously proposed tube writing pen, an inner tube writing pointis designed to be axially displaced in an outer tube writing pointagainst the pressure of a spring so that either the inner tube writingpoint or the outer tube writing point is effective, depending upon thepressure applied to the pen, in other words this tube writing pen can beused for drawing lines of different thickness, although the change inthe thickness of the lines drawn is sudden rather than steady. In orderto be able to draw or write with this previously proposed tube writingpen, the pen has to be held substantially vertical so that the frontsurface of the particular tube writing point rests on the writingsurface. This previously proposed pen cannot be used for writing ordrawing when held at an angle, as is usually the case with tube writingpens.

Various attempts have already been made to produce a writing instrumentwhich does not use a nib in the usual sense, but instead has a writingpoint which is completely symmetrical so that with this writinginstrument it is possible to write or draw at any angle of rotationabout its longitudinal axis and, in particular, even at an obliqueangle. One group of writing instruments of this kind uses an internallyhollow writing point which tapers towards the front and which, towardsits front end, has openings, whilst the actual point is closed. Thelaterally extending openings enable the pen to be used to some extent atan angle, although there are closed zones between the individualopenings in the peripheral direction, as a result of which the linethickness at a constant oblique angle is not althogether independent ofrotation of the writing instrument about its longitudinal axis becausein one instance an opening may be in direct contact with the writingsurface whilst, on another occasion, a closed zone between two openingsmay be in contact with the writing surface. Particular difficulties areencountered with these writing points in cases where it is desired towrite or draw in an exactly vertical position because, in this case, theclosed point is in contact with the writing surface and, especiallywhere the writing surface is rigid, there is no connection to theopenings.

Another difficulty of writing instruments of this kind is that theopenings become clogged if the Indian-ink or writing-ink dries and,thereafter, the writing instrument can only be made to write again withconsiderable difficulty.

Since, in addition, these conventional writing points can only beproduced with sufficient precision at concarry out in view both of theminiscule dimensions involved and of the precision required.

in another writing instrument for Indian-ink or writing-ink which isalso said to write effectively at an angle, a central opening into whichor from which projects a pin designed for displacement to a greater orlesser extent, if formed in the hollow writing point which taperstowards the front. Unfortunately, this writing instrument is attended bybasically the same difficulties as other previously proposed writinginstruments, because when the writing instrument is placed vertically onthe writing surface so that it rests on the tip of the pin, writing isgenerally impossible whereas, when the pin is pressed in, the pen writeswith the line thickness determined by the central opening. If the pin isnot displaceable, it is not possible to'write or draw with the pen heldvertically and only to a very limited extent when the pen is held at anangle.

According to the present invention there is provided a tube writing pen,comprising two writing tubes arranged coaxially one inside the other,the writing tubes communicating with an ink reservoir at their rearends, and the inner writing tube being arranged for limited movement inand with respect to the outer writing tube, at least in the axialdirection, a cleaning wire which projects into the inner writing tube,and a drop weight which is attached to the cleaning wire at the endthereof adjacent the ink reservoir, the interior of the outer writingtube being widened frustoconically at its writing end, whilst the outerwall of the inner writing tube has a complementarily frustoconicallywidened writing zone with a rounded end face.

Thus, the present tube writing pen comprises two writing-ink orIndian-ink dispensing zones one of which is formed by the centralopening of the inner writing tube and the other of which is formed bythe annular gap formed between the frustoconical front end of the outerwriting tube and the correspondingly frustoconically widened front zoneof the inner writing tube. Accordingly the present pen can be used in avertical position in which it dispenses writing-ink or Indian-inkthrough the inner writing tube, whilst, in an inclined position, thewriting fluid is generally dispensed through the inner writing tube andthe annular gap working in conjunction with one another.

Both the outer wall of the outer writing tube towards its front end andthe front end face of the inner writing tube are preferably rounded offso that, for example, part of asphere is formed and smooth,nonscratching writing or drawing is possible in every possible writingposition. In this embodiment, the frustoconical extension of the annulargap preferably extends perpendicularly of a tangent to the sphericalsurface in the vicinity of the annular gap.

Since the inner writing tube is designed for limited movement in theaxial direction and, preferably, also for limited movement transverselyof the longitudinal axis, it is displaced to some extent when the pen isplaced on the writing surface so that, especially when the pen is heldat an angle, whereby the size of the annular gap in the contact zone isvaried in dependence upon the pressure applied so thatpressure-sensitive writing is possible.

The inner writing tube can be displaceably mounted in the outer writingtube in a number of different ways. One very simple method of doing thisis to widen the rear end of the inner writing tube so that it is able torest on a shoulder of the outer writing tube which forms a rear contactsurface.

In order to enable the invention to be more readily understood,reference will now be made to the accompanying drawings, whichillustrate diagrammatically and by way of example an embodiment thereof,and in which:

FIG. 1 is a side elevation of a tube writing point for a tube writingpen, and

FIG. 2 is a diagrammatic section through part of the front zone of thetube writing point shown in FIG. 1.

The tube writing point shown in FIG. 1 consists of an outer bodycomprising an inner compartment which communicates with a reservoir forwriting-ink or Indian-ink and in which a drop weight 4 is arranged. Thisdrop weight is designed for movement at least in the axial direction ofthe tube writing point and, at its front end, carries a cleaning wire 3(FIG. 2) which projects into an inner writing tube 1. The drop weight isprevented from dropping out in conventional manner by means of a clip 6.

In addition, a compensating chamber 5 is formed on the outer surface ofthe outer body and extends in the vicinity of a thread for fixing thewriting point in place, the compensating chamber communicating at itsupper end with the ink reservoir or the inner compartment and, at itslower end, with the surrounding atmosphere. The mode of operation andfunction of a compensating chamber of this kind are known.

A fixed outer writing tube 2 is inserted into the front end of a casingof the writing point and the inner writing tube 1 is arranged coaxiallyin the outer writing tube 2. Both writing tubes 1 and 2 communicate attheir rear ends with the ink reservoir.

As can be seen from FIG. 2, the interior of the outer writing tube 2 iswidened frustoconically at its front end 8, whilst the front zone 7 ofthe inner writing tube 1 is correspondingly frustoconical so that anannular gap is formed in this zone between the inner and outer writingtubes, this annular gap 11 communicating with the ink reservoir throughthe annular gap between the inner and outer writing tubes.

As can readily be seen from FIG. 2, the inner writing tube 1 can onlymove rearwards to a limited extent in the axial direction of the tubewriting point because the frustoconical widenings come into contact withone an other in the front zones. The axial movement of the inner writingtube 1 towards the front is limited by a widening provided at the rearend which comes into contact with a shoulder-like widening 9 of theouter writing tube 2. Assembly of the inner writing tube is readilycarried out by inserting the inner writing tube which, initially, is notwidened at its rear end into the outer writing tube 2, and then wideningits rear end.

The outer wall, in the vicinity of the front end 8 of the outer writingtube, and the end wall of the inner writing tube 1, in the zone 7, arerounded off with substantially the same radius of curvature in such away that they form part of a sphere. This partial sphere is particularlysuitable for use as the writing point because the parts of the spherecan be moved smoothly without scratching over a writing surface.

If the tube writing point is used for writing or drawing in a verticalposition, the writing-ink or Indian-ink flows to the point solelythrough the central bore in the inner writing tube 1, and the pen worksin the same way as a conventional tube writing pen. In addition, in thisposition, the inner writing tube is moved axially to the rear so that,on the one hand, the widened zone 10 moves out of contact with thesurface 9 so that writingink or Indian-ink is able to flow into theannular gap between the inner and outer writing tubes, whilst on theother hand particles of writing-ink or Indian-ink which have dried inthe aforementioned annular gap are released by the movement of the innerwriting tube, ensuring the flow of writing fluid to the annular gap 11.

If the pen is used at an angle, the zone between the longitudinal axisand the annular gap generally comes into contact with the writingsurface which, in the case of a non-rigid surface, means that writingfluid flows onto the writing surface both from the annular gap and alsofrom the central bore. The size of the annular gap in the dispensingzone is influenced by the pressure applied to the inner writing tubewhich is able to move both in the axial direction and also to a limitedextent transversely of the longitudinal axis, in other words the flow ofwriting-ink or Indian-ink through the annular gap is governed by thepressure applied.

The present tube writing pen is even able to write in cases where theinclination is increased to such an extent that the pen is only incontact with the writing surface in the vicinity of the annular gap sothat no writing-ink or Indian-ink is available from the central bore inthe inner writing tube. In this case, too, the line thickness isgoverned by the intensity of the pressure applied.

Thus, the present pen represents a writing instrument which can be usedboth in a vertical position and also at an angle, despite rotationabout'its longuitudinal axis, and allows pressure-sensitive writing ordrawing, as would otherwise only be possible with a pen holder.

I claim:

1. A tube writing pen comprising:

A. an outer writing tube;

B. an inner writing tube coaxially spacedly positioned within said outerwriting tube and forming therebetween an annular gap;

C. an ink reservoir in communication with both said tubes at the rearends thereof and the annular gap therebetween;

D. said inner writing tube being mounted for limited relative movementin an axial direction and limited movement transversely of thelongitudinal axis within said outer writing tube;

E. a cleaning wire projecting into said inner writing tube and having adrop weight attached at the end proximate said ink reservoir;

F. said outer writing tube having a bore frustoconically widened at thewriting end thereof;

G. said inner writing tube having the wall thereof frustoconicallywidened at the writing end thereof correspondingly and complementarilyto the frustoconical widened end of said outer writing tube and formingan annular gap therebetween for an ink flow passage constituting awriting zone;

l-I. said inner and outer writing tubes terminating at the writing endsthereof in rounded end faces having rounded edges and which rounded endfaces have substantially the same radius of curvature andcomplementarily constitute portions of sphere and conjointly form asmooth rounded Writing surface face for varied angular writing positionsof said P 1. the frustoconical surfaces of the inner and outer writingtubes each extending perpendicularly of a tangent to the rounded writingface and terminating in the writing surface face of the sphere;

J. limited axial and transverse movements and resultant displacement ofsaid inner writing tube in said outer tube when said pen is placed on awriting surface and disposed at an angle thereto varying the size ofsaid annular gap in the contact zone in dependence upon pressure appliedfor pressuresensitive writing control and said rounded edges precludingerratic and scratchy writing; and

K. the ends of said inner and outer writing tubes conically widenedwriting ends of said tubes.

1. A tube writing pen comprising: A. an outer writing tube; B. an innerwriting tube coaxially spacedly positioned within said outer writingtube and forming therebetween an annular gap; C. an ink reservoir incommunication with both said tubes at the rear ends thereof and theannular gap therebetween; D. said inner writing tube being mounted forlimited relative movement in an axial direction and limited movementtransversely of the longitudinal axis within said outer writing tube; E.a cleaning wire projecting into said inner writing tube and having adrop weight attached at the end proximate said ink reservoir; F. saidouter writing tube having a bore frustoconically widened at the writingend thereof; G. said inner writing tube having the wall thereoffrustoconically widened at the writing end thereof correspondingly andcomplementarily to the frustoconical widened end of said outer writingtube and forming an annular gap therebetween for an ink flow passageconstituting a writing zone; H. said inner and outer writing tubesterminating at the writing ends thereof in rounded end faces havingrounded edges and which rounded end faces have substantially the sameradius of curvature and complementarily constitute portions of sphereand conjointly form a smooth rounded writing surface face for variedangular writing positions of said pen; I. the frustoconical surfaces ofthe inner and outer writing tubes each extending perpendicularly of atangent to the rounded writing face and terminating in the writingsurface face of the sphere; J. limited axial and transverse movementsand resultant displacement of said inner writing tube in said outer tubewhen said pen is placed on a writing surface and disposed at an anglethereto varying the size of said annular gap in the contact zone independence upon pressure applied for pressuresensitive writing controland said rounded edges precluding erratic and scratchy writing; and K.the ends of said inner and outer writing tubes proximate said inkreservoir having complementarily frustoconically widened inner endportions, axial movement of said inner tube with respect to said outertube being limited in a forward direction by coaction of said widenedinner end portions, and in reverse direction by coaction of saidfrustoconically widened writing ends of said tubes.